Although spread over three days, United Islands doesn't really hit its stride until Saturday the 21st, when three of Prague's river islands -- Střelecký ostrov, Dětský ostrov and Ostrov Kampa -- stage four free all-day concerts.

Billed as the "biggest ska punk event in Europe," this three-day festival also brings rock 'n' roll, hardcore, reggae, indie-rock, breakbeat, jungle and hip-hop acts to a village near Tábor, around 100 kilometers south of Prague.

Despite attracting more than 20,000 visitors and a host of international names, Sázavafest's riverside setting, 60 kilometers southeast of Prague, gives it a more laidback feel than many of its rivals.

Now in its 21st year, the Václav Havel-endorsed "Czech Woodstock" remains true to its alternative roots, bringing a mighty line-up of bands and good vibrations to an amphitheatre in Trutnov, around 120 kilometers northeast of Prague.